1. Field of the Invention
The present invention is related to one-time-programmable (OTP) memories, and more particularly to data programming methods for OTP memories.
2. Description of the Related Art
With the rapid development of consumer electronic products, solid-state data storage has become increasingly important. The small size, simple structure, and low cost of the solid-state data storage are especially desired for portable consumer products. Solid-state data storage technologies (e.g. EPROM, EEPROM etc.) have been optimized for high-speed applications, resulting in complex and expensive processes.
However, for many consumer applications, low cost is more important than speed. Thus, a non-volatile one-time-programmable (OTP) memory having lower manufacturing cost, in which stored information does not disappear even when the power supply is turned off, is an essential element. The OTP memory is widely used for the purposes of, e.g., redundancy of a large-capacity memory such as a DRAM or SRAM, calibrating of an analog circuit, code storage of, e.g., an encryption key, and storage of management information such as the log in the fabrication process. Furthermore, the OTP memory is characterized by that the data stored therein can only be programmed once. In other words, data modification on any of the memory cells of the OTP memory is not allowed once the memory cell is programmed.
For an OTP read only memory (ROM), data can be written into the memory after leaving the factory, i.e. the operating environment and applications of the memory can be programmed through a write-in operation carried out by users in their premises. Thus, the OTP memory is more convenient to use when compared with other memories, such as a mask ROM.